In dental practice, diagnostic wax-ups are created to visualize and plan restorative treatment, e.g., veneers or crowns on the anterior/front teeth. Diagnostic wax-ups are traditionally created in wax on gypsum casts by the dental laboratory for the dentist who uses it for treatment planning as well as for visualization and discussion of the restorative result with the patient. The dialog between dentist and patient is an important tool for improved patient satisfaction and often enables more expensive treatments. To transfer the design from the diagnostic wax-up to the patient's teeth, the dental technician typically looks at the original diagnostic wax-up and manually tries to replicate this design for the real restorations, incorporating potential comments from the dentist and the patient. This manual replication process is both costly, possibly inaccurate, and time consuming.
Because of the manual labor involved, diagnostic wax-ups are generally expensive, often several hundred US dollars. Creating a wax-up model is also time-consuming, such that the patient generally has to return for another appointment to evaluate it. Because diagnostic wax-ups are models of teeth only, they also fail to convey the full aesthetic impact of a restorative treatment. The visual impression of a patient's smile is also determined by the gingiva and the entire face [1]. Furthermore, a free standing wax-up model cannot convey the lighting to which teeth are subject to inside the mouth. In the field of orthodontics, treatment planning has more commonly involved 3D models of both the teeth and the face, or even the head. Data sources include 2D color pictures of the face and CT scans of the head [2, 3].
WO 2006/065955 discloses methods and systems for orthodontic treatment including a method for generating a photo-realistic image of a predicted result of a dental treatment on a patient, the method comprising: acquiring one or more images of the patient's pre-treatment face and teeth; generating a 3D digital model of the patient's pre-treatment face and teeth from the images of the patient's pre-treatment face and teeth; acquiring a 3D digital model of the patient's pre-treatment tooth arch; acquiring a 3D digital model of the patient's predicted tooth arch resulting from the treatment; generating a 3D digital model of the patient's predicted face and teeth from the 3D digital models of the patient's pre-treatment face and teeth, pre-treatment tooth arch, and predicted tooth arch; and rendering a photo-realistic image from the 3D digital model of the patient's predicted face and teeth.
WO 2004/098378 relates to orthodontic treatment and discloses a system for use in diagnosis and planning treatment of a human patient, comprising: a general purpose computer system having a processor and a user interface; a memory accessible to said general purpose computer system storing a) a first set of digital data representing patient craniofacial image information obtained from a first imaging device, and b) a second set of digital data representing patient craniofacial image information obtained from a second image device different from said first image device, said first and second sets of data representing at least in part common craniofacial anatomical structures of said patient, at least one of said first and second sets of digital data including data representing the external visual appearance or surface configuration of the face of the patient; and a set of computer instructions stored on a machine readable storage medium accessible to said general purpose computer system, wherein said set of instructions comprises instructions for causing said general computer system to: 1) automatically, and/or with the aid of operator interaction, superimpose said first set of digital data and said second set of digital data so as to provide a composite, combined digital representation of said craniofacial anatomical structures in a common coordinate system; 2) displaying said composite, combined digital representation of said craniofacial anatomical structures to a user of said system.
Thus, in the field of orthodontics, treatment planning involving 3D models of both the teeth and the face are known.
US 2008/153061 discloses a method for planning and performing dental treatments, comprising: an acquisition phase of a set of data relating to the position, to the conformation and to the dimension of at least one site inside the oral cavity of a patient who has to undergo a dental treatment and relating to the conformation of at least one portion of the face of said patient; a design phase of a virtual prototype of at least one dental prosthesis that can be fitted at said site during said treatment starting from said set of data and by means of a software program implemented on a computer; a determination phase, by means of said software program and starting from said set of data and from said virtual prototype of the dental prosthesis, of at least one virtual model suitable for visually reproducing said portion of the face following the fitting of said dental prosthesis; a preparation phase of said site by means of a dental instrument, with the assistance of said software and starting from said virtual prototype of the dental prosthesis and from said virtual model, before the installation and the manufacture of said dental prosthesis.
US 2008/153061 does not describe how to combine the various sources of geometry information, especially of the teeth, which are represented in both the scan of the face and that of the oral cavity. Neither does US 2008/153061 describe how to transfer the results of the design phase to the actual post-preparation dental geometry. Furthermore, US 2008/153061 assumes the reading phase of the virtual impression to be performed by the same dental instrument that executed the preparation of the oral site.
WO 2009/091438 discloses a method for designing a custom dental device, comprising the steps of: obtaining a set of time-based 3-dimensional images of the oral anatomy of a person during jaw motion; obtaining 3-dimensional data of a dental object of the person; registering the 3-dimensional data of the dental object to at least one of the time-based 3-dimensional images; using the time-based 3-dimensional images and registered 3-dimensional data to design a dental device.
WO 2009/091438 assumes that the 3-dimensional images be acquired at a rate of 50 per second; however, no such scanner exists at present nor is it disclosed. Furthermore, it appears unrealistic that the supposedly required accuracy of tracking dental objects, where the accuracy is about 20 m, can be achieved with any of the technologies referenced, nor is any new appropriate technology disclosed.
In all, it remains a problem to provide improved systems and methods for planning and visualizing dental restorations on teeth of a patient.